This study focuses on the cognitive functioning of patients in hospital-based clinical research. Participation in medical research is stressful for most patients. Therefore, the informed consent procedure is executed in relatively stressful circumstances. Even after carefully planned informed consent procedures are carried out, patients may not fully process the nature and implications of the medical research in which they are participating. The research focuses on the question of how level of cognitive functioning and anxiety influence the patient's understanding of disease and treatment in a research setting. Participants are child, adolescent, and adult in-patients and a comparison group of healthy participants. Psychological assessments are standardized tests and interviews.